Trying to use my iMac (late 2009) as a monitor for a MacBook pro (mid 2012)

Can I connect my MacBook Pro (Retina, Mid 2012) to my late 2009 27" iMac using an HDMI to mini display port cord? I thought that is what I read to do online and purchased it and it does not do anything when I do cmmd+ f2.

If that is not the cord to use, I've looked for a thunderbolt to mini display port cord and don't think it exists? Can I use a thunderbolt to thunderbolt in this case even though the iMac only has a mini display port input?

What cord do I need to purchase to use my imac as a display monitor for my macbook pro?